Related Resources

Reducing Toxic Pollution from Power Plants

On March 16, 2011 EPA proposed Mercury and Air Toxics Standards, the first national standards to reduce emissions of toxic air pollutants...


Utility Air Toxics Determination

Regulatory Finding on the Emissions of Hazardous Air Pollutants From Electric Utility Steam Generating Units


UNEP Global Mercury Assessment

Mercury is a global threat to human and environmental health. This report, focusing on anthropogenic emissions of mercury and their...


MATS Measurement & Reporting Documentation

In its Federal Register publication of the Mercury and Air Toxics Rule, EPA spelled out reporting requirements to document compliance...

EPA Compliance

The Environmental Protection Agency (EPA) issues rules governing the amounts and types of chemicals and substances that can be released into the environment, including those that come from burning coal at the country’s utility plants and industrial boilers. Federal standards in many countries including the United States are requiring power plants to limit their emissions of hazardous air pollutants (HAPs) like mercury, arsenic and metals.


The EPA’s new MATS rules were finalized to reduce air pollution from coal-fired as well as oil-fired power plants under the Clean Air Act Amendments. Emissions standards set under the Hazardous Air Pollutant (HAP) program are federal air pollution limits that existing individual facilities must meet. Under the law, the EPA set emission standards for existing sources at the average emission level achieved by the best performing existing sources.

These rules set emissions limitation standards for mercury and other toxic air pollutants, reflecting levels achieved by the best-performing sources currently in operation. The final rule sets standards for EPA-delegated HAPs emitted by coal- and oil-fired electric generating units (EGUs) with a capacity of 25 megawatts or greater. These standards are incorporated into state major source operating permits that are maintained for each coal-fired generating unit in a utility’s fleet.

On December 27, 2018, EPA issued a proposed revised Supplemental Cost Finding for MATS and the Clean Air Act required “risk and technology review.

For detailed information about the rules, the standards and their timing, visit

Boiler MACT

In addition to the 1,400 coal-fired power plants currently operating in the US, there are approximately 13,500 (according to the EPA) industrial boilers subject to emission limits for certain HAPs, 600 of which depend upon coal for their operations. Like power plants, these boilers can release harmful pollutants into the atmosphere, and their emissions are governed by rules developed by the EPA. In the case of these boilers, the Clean Air Act provisions limit the release of mercury and other toxic air pollutants.

The EPA issued two rules governing sources of HAPs for commercial and industrial boilers. These rules are collectively known as the Boiler MACT rules and impact facilities that burn coal or fuel oil and are a commercial or industrial operation. The MACT rules cover both Major Sources, those boilers located at sources that emit 10 tons/yr of a single HAP or 25 tons/yr of all combined HAPs, and Area Sources, affected boilers that are not considered Major Sources.

For Major Sources the MACT rules place numerical limits on the release of mercury, CO, particulates and hydrogen chloride. All existing boilers of certain heat input capacity must conduct an energy assessment.

For Area Sources, the rule limits emissions for mercury, CO and particulates for both existing and new coal boilers. Boilers under 10 MMBtu/hour are not subject to emission limits but must have tune-ups every 2-5 years. For existing boilers greater than 10 MMBtu/hr heat input, the rule requires an energy assessment. For complete info, visit